Benefits of fert injections for established deciduous trees??

If you do plant/tree fertilization, what is your opinion of the value of fert injections of deciduous trees that are at least 5 years old? I have a customer who wants it done and frankly I have read some articles that say that the benefits are only marginal once a tree has become establsihed. Yet I know the biggger fert companies push this....personally I dont think its worhtwhile but maybe I'm wrong (I have seen great results with systemic injections for birch diseases etc....so I do support that process) just not sure about the "food" injections...thanks

I think the benefits would be rather unnoticeable for established trees, but there are still benefits. Injections wont produce immediate growth, but they are proven to aid the plant in root growth and food storage. Some of the benefits I have seen from injecting are: ease of application, no spray rig needed, any size tree can be treated, no drift/leaching of fert.

Some cons: holes have to be put in the tree, although proponents say these are negligable, tough to do evergreens.

You are correct about the disease injections, so I would have to think the fert injections do have some merit.